Today, the Internet is one of the primary tools used for exchanging and communicating information. Increasingly more and more business models, social exchange forums (e.g., dating services), and even commercial and consumer activities are based solely around the Internet. Similar to the telephone system of the early 1900s, businesses and individuals alike are finding that the requirement of the Internet for communication and gathering of information is something they cannot operate without. However, with this growth of dependency on, and use of the Internet, more and more demands are being placed on the performance of the network. This is especially true with high capacity data such as streaming media, including streaming audio and streaming video data. Users who access and exchange audio and video require that consistent monitoring of performance be carried out in order to ensure network quality. A consequence of the need for higher quality of service is the need for more accurate and extensive measurement and usage of bandwidth.
Bandwidth is a term that describes the amount of data that can be transmitted in a fixed amount of time between one or more computers communicating over a network, such as the Internet. The faster the data is exchanged between computers, the higher the bandwidth must be for that connection. Bandwidth estimation is the process of measuring the bandwidth over the network to ensure network quality. Currently, the most widely used bandwidth measurement techniques involve directly measuring the fastest rate that traffic can be sent from one computer to another. This usually entails sending test or probing packets, from a sending device to a receiving device and measuring the time taken to transmit a certain amount of data. Oftentimes, probing packets are sent in pairs (packet pairs) back-to-back, such that the second packet is sent immediately after the first. The node that receives the packets detects the time delay between the two packets upon their arrival. Assuming that all the intermediate routers send the probing packet pairs back-to-back, the arrival time of the first packet also marks the starting time of the second packet. Hence, the time delay detected gives the amount of the time that the network as a whole takes to send the second packet. The receiving node then divides the size of the second packet by the time delay; the result is the estimated bandwidth (bites/sec).
However, while this method of bandwidth estimation can be effective, the sending of probing packets in addition to regular data and control packets further increases the amount of traffic being exchanged over the network. This problem is even more menacing when exchanging large scale data such as video and audio. Moreover, for real-time communication of video and audio data, accurate estimation of the bandwidth is not enough to ensure network quality. Practical methods and tools for adapting to changing network conditions are necessary in order to truly enhance the user experience.